Geriatric experts agree the problem is significant and overwhelming in its complexities.

Dr. Harris says the average person is not well-versed on the aging process, and doctors must deal with an avalanche of material when treating older patients.

Take the recent arrival of the insomnia drug Ambien into the marketplace.

“It was marketed as the perfect medication for older people,” Dr. Harris says. “It wasn’t until it got into the population as a whole that the problems crept up.”

Potential side effects in elderly patients taking Ambien include amnesia, she says.

Dr. Neil Resnick, chief of the division of geriatric medicine and professor of medicine at the University of Pittsburgh School of Medicine, says the good news is that drug companies “are figuring out better and more effective drugs” all the time.

The Food and Drug Administration tries to ensure that each of these drugs isn’t harmful, but the research isn’t sufficient to identify some problems when older people take them, Dr. Resnick says.

A person’s age affects how a drug is absorbed or excreted in the body, he says.

Though companies have begun using older people in their research, the people used often don’t accurately reflect the kind of patients who may end up taking the drug.

“On average, older people have several chronic, coexisting conditions for which they take other medications,” Dr. Resnick says. “As a result, when the drug is approved, there’s very little knowledge as to how that drug will work when given to a 75-year-old person taking eight to 10 other drugs.”

Doctors often are helpless in trying to avoid drug conflicts with their patients, even if they diligently track every medication and known side effect their patients could experience.

“There’s almost no data on this, given how many combinations you can have with diseases or drugs,” Dr. Resnick says.

He laments a generational trend that too often prevents seniors from asking the right questions of their doctors.

“Baby boomers have no qualms about asking those questions, but Depression-era seniors are respectful of physicians and concerned they’ll offend their doctors and look ungrateful.”

The truth is, physicians want inquisitive patients.

“An engaged patient will alert us to the problems they have,” Dr. Resnick says.

Todd Semla, secretary of the New York-based American Geriatrics Society, says the problem of overmedicated seniors “is sizable if you consider the percentage of seniors at risk.”

“Maybe up to 25 percent of seniors are on a medication not appropriate for seniors,” Mr. Semla says.

On average, senior citizens take between four and five medications — up to 12 for those in a nursing home or center.

Not even the older medications prove completely safe for seniors.

“Some of the medications we’re most concerned about have been around a long time,” Mr. Semla says. For example, ibuprofen can cause gastrointestinal bleeding in a small percentage of seniors.

Even an innocent-sounding herbal medication such as St.-John’s-wort, which some people take for depression, can be problematic for seniors.

“It can accelerate the metabolism of many other medications they can be taking,” Mr. Semla says.

Dr. Philip Bryant, a physiatrist and medical director at Good Shepherd Rehabilitation Network in Southeastern Pennsylvania, says some pain medications can, when misused or combined with other drugs, lead to balance problems for elderly patients.

The very nature of the human body makes taking medication a complicated situation to monitor.

“As we grow older, we have less muscle, more fat and less water. The medications we take can be fat soluble or lipid soluble,” which can affect how a drug enters the body, Dr. Bryant says. “We have to adjust the medications to accommodate a person’s ability to absorb and metabolize them.”

Patients and their loved ones can take some simple steps to help alleviate drug complications. The single biggest factor in preventing problems, Dr. Bryant says, is starting and maintaining a list of all the medications the person is taking, even over-the-counter drugs.

“The number of people who do that is low, and the percentage of people who keep it updated is even lower,” he says.

It’s up to patients working alongside their doctors to prevent emergencies.

“We should have a cultural expectation that patients and their families be more aware. They need to be active [in the process],” he says.

Dr. Harris suggests going online to get as much information between doctor visits about drugs and their potential side effects.

“Certain Web sites can help them out,” Dr. Harris says, citing both WebMD and the American Geriatric Society (www.americangeriatrics.org/) as good starting points.